Manufacture of nonporous metal articles



Patented Mar. 14, 1944 7 2,343,978 MANUFACTURE or uoNronoUs. METAE ARTICLES 1 William David Jones, London, England No Drawing. Application July 1, 1940, Serial No.

7 Claims.

This invention relates to the manufacture of metal articles or masses and has as its principal object to produce non-porous articles or masses having a high tensile strength and elongation from brass or bronze powders.

In Great Britain July 7, 1939 According to the process of the present invention a brass or a bronze powder or a mixture of powders containing the elements present in the brass or bronze is subjected to pressure at an elevated temperature of at least 500 C. but below the point of general fusion for example a temperature of between about 500 and 900 C., preferably a temperature between about 600 and 750 C. In general the higher the pressing temperature the greater will be the elongation.

Particularly suitable brasses are those containing about 70% of copper and 30% of zinc whilst particularly suitable bronzes are those containing up to 20% of tin, especially those containing from 5 to 12% of tin and up to 30% of zinc and if desired one or more of the following: up to of nickel, up to 5% of silicon, up to 5% of manganese, up to 10% of lead, up to 5% of chromium,

up to 3% of phosphorus, up to 5% of aluminium and up to 5% of iron.

The process according to the invention may be brasses or bronzes the powders may, if desired, be

mixed with other elements or alloys or compounds-thus for example the presence of nickel, phosphorus and silicon, which assist in obtaining high tensile strength but at the sacrifice of elongation.

Examples of suitable additional elements are silicon, nickel, iron and lead,

If desired calcium hydride, titanium hydride, zirconium hydride, or alkali metal hydrides may be added as described in my specification No. 503,874, whilst furthermore non-metallic elements or fluxes such as mixtures of fluorides and chlorides may be added.

The use of a temperature of between about 600 and 750 C. is particularly advantageous since these are lower temperatures than those employed in 'die casting and are so low that metal dies will withstand the temperatures.

The heating may be effected electrically by resistance or induction.

The die in which the hot pressing is effected may, if desired, be nonmetallic. I

In cases where oxide content is very detrimenta there is the possibility of obtaining a pressing which contains no oxide at all. This can be effected by combining together a process of powder manufacture with the process of pressing. For example the powdered bronze or brass can be manufactured by commiriuting by ball milling, disintegrating, or grinding the massive alloy in a protective atmosphere so that no oxidation takes place, and then introducing the powder into dies and cold pressing it in dies and then'hot pressing, conducting thewhole operations in a protective atmosphere.

After the hot pressing operation the rate of cooling of the product can be controlled, or separate heat treatments may be applied in order to modify the mechanical properties thereof.

After the hot pressing the product can be brought to the/desired size if necessary in ,a press and. it can also be mechanically treated to modify its density or to alter its physical constitution such as by forging, stamping and rolling, if desired whilst still hot.

If desired the product of the invention may have a different composition in different parts thereof, for example by using layers of powders of difl'erent composition as the initial material.

The following examples in which the parts are by weight, illustrate how the process of the invention may be carried into effect:

1. A mixture of 95 parts of copper powder and 5 parts of tin powder was pressed at room temperature in the air, with a pressure of 11 tons per square inch. Thecompact thus formed was then pressed with a pressure of 5 tons persquare inch at 800 C. and cooled in air. The pressing produced had a maximum stress of 22.5 tons per square inch, a yield point of 12 tons per square inch and an elongation of 4'7 2. A mixture of 93 parts of copper powder and '7 parts of tin powder was treated as in Example 1.

The pressing produced had a maximum stress of 23.5 tons per square inch, a yield point of 12 tons per square inch and an elongation of 3. -A mixture of 91 parts of copper powder and 9 parts of tin powder was treated as in Example 1. The pressing produced had a maximum stress of and a yield point 9 tons per square inch and an elongation of 53%.

elongation comprising cold pressing a pulverulent mass containing a predominant proportion of copper and at least one metal selected from the" group consisting of tin and zinc at a pressure of more than five tons per sgiare inch to form a compact, and again pressing the compact at a pressure less than that employed in the cold pressing step while at a temperature of between about 600 and 750 C. to convert the compact into a non-porous body of high tensile strength and having an elongation of 17 to 75%.

5. A mixture of 83 parts of copper powder,

10.5 parts of zinc powder, 2.5 parts of tin powder and 4 parts of nickel powder was treated as in Example 1. The pressing produced had a maximum stress of 20 tons per square inch, a yield point of 10 tons per square inch and an elongation of 32%.

6. A mixture of 88.5 parts of copper powder, 5.3 parts of nickel powder, 5.4 parts of tin powder and 0.8 part of silicon powder was treated as in Example 1. The pressing produced hada maximum stress of 26 tons per square inch, a yield point of 23 tons per square inch and an elongation of 7. A powdered alloy having the following composition: copper 82.9%, zinc 10.48%, iron 0.54%. tin 5.88% and lead 0.2% was treated as in Example 4. The pressing produced had a maximum stress of 21.5 tons per square inch, a yield point of 12 tons per square inch and an elongation of 46%.

8. A mixture of 70 parts of copper powder and 30 parts of zinc was pressed at room temperature in the air at tons per square inch. The compact thus formed was then pressed with a pressure of 6 tons per square inch at 825 C. and cooled in air. The pressing produced had a maximum stress of 17.5 tons per square inch and an elongation of 30%.

Besides having good tensile properties some of the brasses and bronzes referred to above have also excellent wear resistance properties. From the point of view of improving the wear resistance or bearing properties it is possible to incorporate in their composition small amounts of graphite, lead or other suitable materials.

The processof the present invention has numerous advantages for example cheapness of manufacture, excellent mechanical properties of the product, particularly strength and ductility, freedom from casting defects such as pinholes, controlled grain size and shape, controlled distribution of the alloying constituents, the possibility of adding constituents which do not or only partially alloy, elimination of wastage of metal inherent in casting, melting, and slagging processes, the use of permanent or semipermanent moulds, accuracy oi. sizing, possibility of producing articles characterised in that they are formed around and have embedded in them some pre-formed component, e. g., metallic or non-metallic components, or inclusions of higher or lower density than the main body of the article in order to obtain specialised mechanical or balance characteristics, and the possibility of obtaining alloys having physical or chemical characteristics that are unobtainable by casting methods.

The expression "articles as used in the ap pended claims includes masses.

What I claim is:

1. A process for the manufacture of non-porous metal articles of high tensile strength and 2. A process for the manufacture of nonporous metal articles of high tensile strength and elongation comprising cold pressing a pulverulent mass containing a predominant proportion of copper andat least one metal selected from the group consisting of tin and zinc at a pressure of more than five tons per square inch to form a compact, and again pressing the compact at a pressure less than that employed in the cold pressing step while at a temperature of between about 500 and 900 C. to convert the compact into a non-porous body of high tensile strength and having an elongation of 17 to 75%.

3. A process for 'the manufacture of nonporous metal articles -of high tensile strength and elongation comprising cold pressing a pulverulent mass containing a predominant proportion of copper and at least one metal selected from the group consisting of tin and zinc at a pressure of about ten to eleven tons per square inch to form a compact, and further pressing the compact at a pressure of about five to six tons per square inch while at a temperature of about 500 to 900 C. to convert the compact into a non-porous bodyof high tensile strength and having an elongation. of 17 to 75%.

4. A process for the manufacture of nonporous metal articles of high tensile strength and elongation comprising cold pressing a pulverulent mass of an alloy containing a predominant proportion of copper and at least one metal selected from the group consisting of tin and zinc at a pressure of more than five tons per square inch to form a compact, and again pressing the compact at a pressure less than that employed in the cold pressing step while at a temperature of between about 600 and 750 C. to convert the compact into a non-porous body of high tensile strength and having an elongation of 17 to 75%.

5. A process for the manufacture of nonporous metal articles of high tensile strength and elongation comprising cold pressing a pulverulent mass consisting of a mixture of about 91 to 95 parts of copper powder and of about 9 to 5 parts of tin powder, at room temperature in the air at a pressure of about eleven tons per square inch to form a. compact, and again pressing the compact with a pressure qt about five tons per square inch while at a temperature of about 800 C. to convert the compact into a non-porous body of high tensile strength and having an elongation of 17 to 75%.

6. A process for the manufacture of nonporous metal articles of high tensile strength and elongation comprising cold pressing a pulverulent mass consisting of a mixture of about 85.7 parts of copper powder, 10.7 parts of zinc powder and three parts of tin powder, at room temperature in the air at a pressure of about eleven tons per square inch to form a compact,

and again pressing the compact with a pressure of about five tons per square inch while at a temperature of about 900 C. to convert the compact into a non-porous body of high tensile strength enfi having on elongation of about 53%. pressure of about eleven tons per square inch 7. A /proces for the manufacture of nonto form a, compact, and again pressing the com,-

porous metal articles of high tensile strength pact with a pressure of about five tons per square and elongation comprising c01 1 pressing a. pulinch while at a. temperature of about 800 -C.

verulent mass consisting ot af mixture of about to convert the compact into a, non-porous body 88.5 copper power, 5.3 parts ofenickle powder, 5 of high tensile strength and elongation.

5.4 parts of ,tin powder and 0.8 part of silicon powder at room wmpereture in the air at a WILLIAMDAVID JONES. 

